TU-TESL

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Laser welding can greatly improve the safety and service life of power battery. In the manufacturing process of power battery, there are many laser welding parts, including electrode lug, flip sheet, seal, bus bar, pack module, injection hole package, etc., which can realize series and parallel connection of battery. At the same time, it involves electric core, module, pack, and can also weld various materials such as steel, aluminum, copper, nickel, etc. On the square, laser welding is mainly penetration welding and pulse welding. On the soft battery, it's pulse welding. The principle is that the laser element with high energy density uses heat source for welding, which has good reliability, small contact resistance, high degree of automation and can greatly improve production efficiency. The advantage of laser welding is to improve the connection reliability, lighten the module, reduce the internal resistance of the battery and reduce the heat loss. At the same time, it can work continuously without shutdown, with good welding quality and high flexibility. The difficulty and pain point is that the weldment assembly accuracy is high, and the position of the beam on the workpiece cannot be significantly offset. At the same time, the cost of laser and related systems is high. At present, the market share of head enterprises such as lithium laser welding equipment manufacturers is about 30-40%. At the same time, according to the understanding of high tech lithium battery, and other well-known lithium battery enterprises are involved in the use of laser welding. In the laser welding technology, the relatively outstanding ones are seal pin welding, top cover welding and continuous welding. Seal pin welding is pulse welding because of intermittent heat input, less tin hydrogen and good effect. The development of seal pin welding is divided into two stages, the first stage is 7-8mm / s, the second stage is that the speed has reached 30mm / s, and it will be faster in the future. The first stage of head welding is common head welding, which can only be achieved at 60-80mm / s. because it belongs to deep penetration welding, it is easy to see the hole during the welding process, and it is easy to close at the end of the hole. How can the electronic steam spill out, and it is easy to cause rough surface. The second stage is used by composite welding and high frequency swing welding, which can solve the problem of quick closing of the viewing hole and greatly improve the welding speed. The third stage is like some companies starting new attempts, such as high-speed welding of annular spot and composite welding, which can achieve 300 mm / s. The characteristic of continuous welding is fast speed, but it is easy to form heat accumulation, and there is no micro fracture in the process of instantaneous molten pool cooling. Among them, the continuous laser welding can reach 15 mm / s, and the physical welding can reach 300 mm / s. Generally speaking, lithium battery equipment is usually welded by laser head and galvanometer laser processing head, which can realize the high-speed welding of complex tracks such as S-shaped and spiral shaped, and increase the welding strength while increasing the weld joint area. During the welding process, the MES system can also be connected to record and adjust the welding parameters in real time to ensure more stable and high-quality welding. For laser welding equipment, there are three main development trends. First of all, the laser power of laser welding is increasing. So in the trend of "cost reduction and efficiency increase" of lithium battery equipment, the precision requirements will be higher and higher, and the position accuracy of welding may be higher and higher. Wu Hua'an, general manager of Ted laser, said that laser welding has more controllability in terms of quality and higher welding accuracy. In the future, it will comprehensively replace bolt, adhesive and other methods. For example, the 3000W single-mode group continuous fiber laser newly developed by Ruike laser has higher photoelectric conversion efficiency (≥ 35%), better and more stable beam quality, stronger anti high reaction ability, and more stable and precise cutting effect in cutting thick plates. Secondly, the ability of data collection in application scenarios is enhanced, and the ability to control the effect of laser welding is enhanced. For example, through artificial intelligence and big data algorithm, 3D model simulation and intelligent prediction of welding effect are carried out. For example, Han's laser adopts the combination of high-power galvanometer, robot and 6000W laser, with good welding quality (weld shear force > 1000N, weld fusion depth of 0.5-2mm). The system is compatible with the production of lithium battery modules of various specifications and models, and can realize fast switching. CCD addressing is used to collect data, and positioning is accurate; welding monitoring is used to trace the whole process of products. Finally, stability, security and flexibility are enhanced. Haimu star laser is the representative. The 2000W fiber laser of Apache is integrated into the welding equipment to conduct full welding test on the aluminum box of the battery, which has reached the standards of 0.8m m-1.4mm melting width, 0.6mm-1.1mm melting depth, 60 μ m flanging and 500 μ m bulge value. The laser welding equipment of starfish laser can achieve continuous and stable production. In terms of safety, it can ensure operation, instruction, data and other records, with power-off protection. In terms of flexibility, laser welding can be customized according to the actual product material, process and other requirements. It is worth noting that the annual meeting will be held in Hyatt Hotel, Shenzhen airport. The theme of the annual meeting is the upstream and downstream enterprises in the 500 + lithium battery industry chain, and the top 800 + enterprises will gather in Shenzhen. At that time, according to the application and development trend of laser and laser welding in the production of lithium battery, the industry leaders will share their insights.